Ambulatory infusion pumps are useful for providing a variety of drug therapies, and can be particularly beneficial for therapies that must be delivered over an extended period of time. Some aspects of ambulatory drug pumps are described for example in U.S. Pat. Nos. 4,559,038, 5,531,697, 5,658,252, 5,772,409, 5,823,746, and 5,879,144, the disclosures of which are incorporated by reference herein in their entireties.
The infusion pumps disclosed and described in the above-referenced patents may regulate the conveyance of fluid from a fluid reservoir to a patient. With infusion pumps like or similar to that of the aforementioned '038 patent, a fluid reservoir containing fluid for treating a patient may be held in a cassette having a pressure plate immediately adjacent to a pump control module. A tube for conveying the fluid may couple the fluid reservoir to the patient and provide a medium for conveying the fluid. A pump control module may include a pumping mechanism, having tube engaging members that are capable of engaging and sequentially squeezing the tube against the pressure plate of the cassette, in so-called “peristaltic”-type pumping action. The tube engaging members may include an expulsor and valves on opposite sides of the expulsor.
A variation of the infusion pump described in the aforementioned '038 patent may include a pump control module substantially as described above used in conjunction with a remote fluid reservoir, i.e., a fluid reservoir separate from the pump control module and not in a cassette that is directly coupled to the control module. Typically, in infusion pumps incorporating remote fluid reservoirs, the fluid reservoir may be secured on a holding apparatus, such as a pole, separate from the pump control module instead of in the cassette. The tube conveying the fluid from the remote fluid reservoir to the patient typically extends from the remote fluid reservoir, across a mechanically actionable portion or surface of the pump control module, and to the patient. In particular, in such an arrangement, the fluid-conveying tube may be disposed between the pump control module and a so-called “remote reservoir adapter” or “RRA” that includes a pressure plate, with tube engaging members of the control module squeezing the tube against the pressure plate to provide the aforementioned peristaltic-type pumping action.
While infusion pumps as described have been generally deemed by those in the medical arts to be advantageous in delivering fluids to patients reliably, some variation in delivery accuracy (with respect to volume of fluid delivered) has been observed with some known examples of pumps and pressure plates. It would therefore be desirable to improve pressure plate designs to reduce such variations and improve delivery accuracy.